Preheat the oven to 450 degrees F. Place baking paper onto 2 baking sheets and set aside.
In a small bowl, combine the flour, smoked paprika, paprika, 1 teaspoon of salt, pepper and garlic powder.
In another bowl or shallow dish, whisk together the buttermilk and eggs. Add half of the flour mixture to the buttermilk and beat until smooth and thickened.
In a separate bowl, combine the breadcrumbs, olive oil and remaining teaspoon of salt.
Lightly dredge the onion rings in the flour mixture and then drop into the buttermilk. Drain the excess batter and then dredge in the breadcrumbs. For a thicker coating, chill the coated onion rings for one hour and then repeat this step (as I did).
Arrange on the prepared baking sheets in a single layer. You can place smaller rings inside bigger ones if necessary, just make sure there is space between them.
Spray generously with the cooking spray.
Bake 20 to 30 minutes. Halfway through the cooking time, flip over each onion ring over and spray with cooking spray to ensure even crisping and browning.